Disappearing printed images and a method for creating them

ABSTRACT

In one aspect, the present invention comprises a method and system for creating images that disappear when exposed to light. The method and system are suitable for commercial printing. In another aspect, the invention comprises a printed image that disappears when exposed to light. In yet another aspect, the image reappears when removed from exposure to light, permitting reuse. In a preferred embodiment, the invention comprises a item for amusement, preferably a collectible card, bearing an image that disappears when exposed to light and reappears thereafter when removed from exposure to light.  
     In one preferred embodiment, the invention comprises an image, the image comprising a first image portion and a second image portion, the first image portion and second image portion being substantially visibly distinct before exposure to light by an end user, and the first image portion and second image portion being substantially visibly indistinguishable after exposure to light by the end user.

BACKGROUND

[0001] Color-changing printing techniques have been used to cause images to appear when a color-changing ink is subjected to a color-changing stimulus by the end user. For example, U.S. Pat. No. 5,215,956 describes a color-changing print in which an image appears in response to application of a chemical color-changing agent. Similarly, U.S. Pat. No. 5,443,629 describes a latent image ink for printing games or coloring books which appears in response to application of a developing solution such as ferric chloride. Use of developing agents is typically an irreversible process, allowing the printed image to appear only once. The use of chemical developing agents in amusement devices generally renders them unsuitable for play for small children.

[0002] Inks and prints which cause indicia to appear in response to light are also known, such as the amusement devices of U.S. Pat. No. 5,190,298. Such inks and prints are an improvement over those that require chemical developing agents.

[0003] Disappearing inks for drawing or writing are also known. Such inks are useful for individual writing or drawing, but are unsuitable for printing because what is printed may disappear before the product is used. Printed disappearing and reappearing images have been described in works of fiction, such as Harry Potter and the Sorcerer's Stone by J. K. Rowling (describing trading cards). However, before the present invention, no practical technique for creating such images has existed.

SUMMARY

[0004] In one aspect, the present invention comprises a method and system for creating images that disappear when exposed to light. The method and system are suitable for commercial printing. In another aspect, the invention comprises a printed image that disappears when exposed to light. In yet another aspect, the image reappears when removed from exposure to light, permitting reuse. In a preferred embodiment, the invention comprises an item for amusement preferably a collectible card, bearing an image that disappears when exposed to light and reappears thereafter when removed from exposure to light.

[0005] In one preferred embodiment, the invention comprises an image, the image comprising a first image portion and a second image portion, the first image portion and second image portion being substantially visibly distinct before exposure to light by an end user, and the first image portion and second image portion being substantially visibly indistinguishable after exposure to light by the end user. In another preferred embodiment, the first image portion and second image portion comprise visibly different colors before exposure to light by an end user, and the first image portion and second image portion comprise substantially a single color after exposure to light by the end user.

[0006] In another embodiment, the invention comprises a system and a method for drawing images that disappear when exposed to light.

[0007] In one preferred embodiment, the invention comprises an item for amusement, such as a collectible card, bearing an image that disappears when exposed to light sufficiently slowly to be viewed, preferably by at least two persons, but sufficiently quickly that the image begins to fade noticeably within a typical viewing period. The image preferably fades noticeably within about 10-15 seconds and substantially disappears within about 45-60 seconds.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 schematically depicts an example preferred collectible card embodiment comprising a disappearing image.

DETAILED DESCRIPTION

[0009]FIG. 1 depicts an example preferred item for amusement, in the form of a collectible card, in accordance with the present invention. The card 109 comprises an image (in this example, depicting a wizard) printed on a cardboard substrate. The image comprises a line drawing 115 and a second image portion complementary to the lines of the line drawing and making up the rest of the image, both inside (for example, 110 and 112) and outside (for example, 114) of the line drawing 115. Before exposure to light, the line drawing is visibly distinct from the second image portion, preferably a visibly different color. Upon exposure to light by an end-user (such as a child playing with the card), the color of the line drawing 115 or the color of the second image portion, or both, changes, so that after full exposure, the line drawing 115 and the second image portion are substantially indistinct, comprising substantially the same color. Thus, when fully exposed, line drawing 115 substantially disappears. As used herein, the term “color” means color or any ombination of one or more color attributes such as hue, color value, saturation, or intensity, and includes (without limitation) black, white, clear, or substantially colorless. The term “image” includes, without limitation, any picture, graphic, text or other indicia or combination thereof.

[0010] The color change is preferably accomplished by printing line drawing 115 or the second image portion, or both, with photochromic ink. Photochromic inks compatible with the present invention are available for example from Color Change Corporation (see www.colorchange.com) of Addison, Ill. Chromatic Technologies, Incorporated (see www.interactivecolors.com) of Colorado Springs, Colo., and International Ink Company (see www.iicink.com) of Gainesville, Ga.

[0011] In one preferred embodiment, line drawing 115 is printed with a photochromic ink or inks which changes from an unexposed color to an exposed color upon exposure to light. The second image portion is printed with a conventional ink or inks of a color that is substantially the same as the exposed color of the Photochromic ink. The unexposed color of the line drawing is visibly different from the second image portion. After exposure to light, the exposed color of the line drawing 115 is substantially the same as the second image portion, and the line drawing 115 substantially disappears.

[0012] In another preferred embodiment, line drawing 115 is printed with a conventional ink, and the second image portion is printed with a photochromic ink having an unexposed color visibly different from the line drawing 115, and an exposed color substantially the same as the line drawing 115. After exposure to light, the exposed color of the second image portion is substantially the same as the line drawing, and the line drawing 115 substantially disappears.

[0013] In another preferred embodiment, the entire printed surface of the card 109, is printed with photochromic ink which changes from an unexposed color to an exposed color upon exposure to light. In addition, the line drawing 115 is printed with a conventional ink or inks having a color or colors such that when the card 109 is exposed to light, the color of the line drawing 115 (comprising conventional ink and photochromic ink) is substantially the same as the exposed color of the second image portion, and the line drawing 115 substantially disappears. This embodiment does not require that the line drawing and the second image portion be registered by the printer. In this preferred embodiment, the photochromic portion is preferably printed first, but alternatively, the photochromic ink may be printed after the line drawing 115.

[0014] In another preferred embodiment, the Photochromic portion is printed after the conventional portion, and changes from a substantially transparent or translucent unexposed color to a substantially opaque exposed color.

[0015] In an alternative embodiment for drawing or painting, a surface printed with multicolor photochromic ink is provided, which changes from an unexposed color to an exposed color upon exposure to light. A marking tool is also provided with conventional ink having a color such that when the surface is marked with the marker and then exposed to light, the color of the markings is substantially the same as the exposed color of the surface, and the markings substantially disappear. Preferably a kit for drawing is provided comprising one or more marking tools and one or more drawing surfaces printed with photochromic ink. In a less preferred embodiment, the drawing surface is printed with conventional ink, and the marking tool is provided with Photochromic ink.

[0016] The present invention is not limited to collectibles or to line drawings or to single iunexposed colorations, but may include any image or image portion which, together with an adjacent image portion, takes on a substantially uniform color upon exposure to light. Similarly, the invention is not limited to cardboard substrates, but may be implemented on any surface that will support printing or drawing.

[0017] A preferred embodiment uses photochromic inks that can change colors repeatedly, and which revert to substantially the unexposed color when removed from exposure to light. Color-change times and end-point colors will typically vary depending upon the chosen photochromic ink composition and the intensity of the light at wavelengths to which the photochromic inks respond, and will typically be shorter in direct sunlight than in dimmer or more diffuse light.

[0018] In the preferred collectible embodiment, such as a collectible card or playing card, the line drawing 115 or other image preferably begins to noticeably fade within a typical viewing period for collectible cards in outdoor daytime conditions, preferably within about 15 seconds, more preferably within about 10 seconds and alternatively within about 5 seconds. The image preferably does not fade from view immediately, but fades gradually over a period in which it may be viewed by two or more persons, preferably within about 60 seconds, more preferably within about 30 seconds, or alternatively within about 90 seconds. The line drawing or image preferably substantially disappears within a typical viewing period, preferably within about 60 seconds, more preferably within about 30 seconds, or alternatively within about 90 seconds. Thus the card begins to noticeably fade quickly enough that a child playing with the card would be unlikely to overlook the effect, but not so quickly that the image or line drawing could not be seen or shown to a playmate. Reversion times are preferably also short enough that the child can view the reversion, preferably within about 60 seconds, more preferably within about 30 seconds, or alternatively within about 90 seconds. Disappearance and reversion times may be varied depending on the subject of a particular collectible card. For example, evil characters may take longer to disappear than good characters, or characters having particular powers or other characteristics may persist longer than other characters.

[0019] Images printed in accordance with the present invention may advantageously be used as illustrations in a book. When the book is closed, no light will reach such an illustration, and the illustration will therefore typically be visible when the reader turns to the page bearing the illustration. Thereupon, light will fall on the illustration, and the illustration will fade from view (in whole or in part) while the reader is turned to the page. 

What is claimed is:
 1. A printed surface comprising an image that substantially disappears within a predetermined interval in response to exposure to light by an end-user.
 2. The printed surface of claim 1, wherein the image substantially reappears within a predetermined interval when removed from exposure to light.
 3. The printed surface of claim 1, further comprising: a background comprising a color that does not substantially vary color when exposed to light; a figure comprising an unexposed figure color visibly different from the background color, the unexposed figure color changing to an exposed figure color substantially the same as the background color when exposed to light.
 4. The printed surface of claim 1, wherein the background and figure comprise a portion of a larger image.
 5. The print of claim 3, further comprising: a second background color; a second figure comprising a second unexposed figure color visibly different from the second background color, the second unexposed figure color changing to a second exposed figure color substantially the same as the second background color when exposed to light.
 6. A line drawing that substantially disappears within a predetermined interval in response to exposure to light by an end-user.
 7. A kit for drawing line drawings that substantially disappear comprising a marking tool for creating a first image portion on a surface, the surface comprising a second image portion, the first image portion having a different color than the second image portion before exposure to light by an end-user, and the first image portion having substantially the same color as the second image portion after exposure to light by the end-user.
 8. The printed surface of claim 1, the image comprising a first image portion and a second image portion, comprising a marker for creating a first image portion on a surface, the surface comprising a second image portion, the first image portion having a different color than the second image portion before exposure to light by the end-user, and the first image portion having substantially the same color as the second image portion after exposure to light by the end-user.
 9. The printed surface of claim 8, wherein the image substantially reappears within a predetermined interval when removed from exposure to light.
 10. A method for printing a disappearing image, comprising the steps of printing a first image portion and printing a second image portion, the first image portion having a different color than the second image portion before exposure to light by the end-user, and the first image portion having substantially the same color as the second image portion after exposure to light by the end-user.
 11. A toy comprising an image that noticeably fades within 15 seconds and substantially disappears within 60 seconds in response to exposure to light.
 12. A collectible comprising an image that substantially disappears in response to exposure to light.
 13. The collectible of claim 12, wherein the image substantially reappears in response to removal from exposure to light.
 14. A set of collectibles comprising images that substantially disappear within a predetermined interval in response to exposure to light, wherein the predetermined interval varies based on the subject of each collectible. 